Flood events are major drivers of soil erosion and sediment yield on the Loess Plateau, where extensive ecological restoration has been implemented. This study investigates runoff-sediment dynamics by analyzing 215 flood events recorded in the Chabagou watershed (1959-2022), with a focus on changes under intensifying restoration efforts. Using long-term hydrological and rainfall data, we applied cluster and discriminant analyses to classify flood events based on sediment hysteresis loops and evaluated variations across three management periods (1959-1979, 1980-1999, and 2000-2022), characterized by progressive increases in check dam construction and vegetation recovery. The results show that the floods characterized by short duration, low peak flow, and low sediment concentration were predominant, accounting for 77.7% of the recorded 215 events. A clear decreasing trend was observed, with average sediment yield and peak discharge declining by approximately 68% and 52%, respectively. Anticlockwise hysteresis loops were most common (45.6%), followed by complex (27.9%) and figure-of-eight loops (23.7%). The proportion of figure-of-eight loops increased notably from 17% to 39%, indicating reduced sediment connectivity due to large-scale ecological restoration. Extreme rainfall events consistently produced complex hysteresis patterns, influenced mainly by rainfall intensity but increasingly modulated by human interventions. These results highlight adaptive watershed management strategies that target figure-of-eight and complex flood events to mitigate erosion and flood risks.

近年来,由于水土保持效果无法达到管理目标,高速公路建设中大量弃渣堆置场地发生多次变更.其原因在于弃渣场变更与水土保持的关系还不清楚.本文以兰海国家高速公路遵义至贵阳段公路扩容工程为例,说明弃渣场变更的主要原因,包括:主体工程施工进度、弃渣场选取地点存在安全隐患、弃渣场便道不方便通行或不满足运输条件、弃渣场征地困难等.同时提出了水土保持措施.研究结果可为弃渣场选址、变更处理提供理论指导.

Understanding the changes in soil and water loss is important to make the regional sustainable development strategies for administrative department. This study compiled a series of dataset from 2012 to 2019 at the county scale to investigate the changes in soil and water loss in three government divided regions, i.e., urban region (UR), northeast region (NER) and southeast region (SER) in Chongqing Municipality, China. The area percentage of soil and water loss over moderate degree (OMD) in each year and change rate for the area of soil and water loss (CR) on the basis in 2012 for each region were compared. The area of soil and water loss decreased by 22.3%, 18.7% and 14.2% in the UR, NER and SER, respectively, from 2012 to 2019. The area of soil and water loss in NER almost accounted for 50% of the total area of soil and water loss in Chongqing City. The OMD decreased from 66.06% in 2012 to 24.84% in 2019. The CR always presented significantly declined trend (P < 0.05) with the year in the UR, NER and SER, respectively. Our results are valuable to developing reasonable conservation strategies for the local government to control soil and water loss.

干旱沙漠区水资源是改善生态环境和促进动植物生存的关键.综合古尔班通古特沙漠研究成果,分别对该沙漠气候特征、水分分布和水分来源、水分循环和生态水文过程等方面进行归纳,指出现有研究存在的不足.在此基础上对古尔班通古特沙漠今后研究的方向和内容进行展望,指出将该沙漠不同水体纳入整体研究,以期丰富该沙漠生态水文机制和进一步探讨干旱区水文循环过程.

A large number of radionuclides, produced by nuclear waste and nuclear accidents, can cause radioactive contamination in the agricultural and aquatic ecosystems. It is necessary to optimize the remediation of agricultural areas polluted by radionuclides using innovative monitoring and prediction techniques. To mitigate radioactive contamination in farmland soil and effectively protect groundwater, some measures should be taken against on field investigation, laboratory experiment and model prediction. In this study, the HYDRUS-1D model was used to simulate the vertical migration of 137 Cs and 60 Co in farmland soil in northern China calibrating by the soil lysimeter experiment, and the scenario simulations of 137 Cs and 60 Co migration were conducted under different radioactive levels. Results showed that the order of sensitivity in saturated water content (θ s ), residual water content(θ r ), saturated hydraulic conductivity (K s ) and distribution coefficient (K d ) applied in HYDRUS 1D model was K d > θ s > θ r >K s . The simulated concentrations ​​of 137 Cs and 60 Co in Brown soil and Aeolian sandy soil on day 175 and 355 were significantly positively correlated with the measured values​​ (r>0.90, p<0.01). The verification results showed that the predictive values on the 577 th day were also significant positive correlated with the measured values ​​(r>0.90, p<0.01). The RMSE, CRM and NRMSE calculating by simulated and measured values ​​of 137 Cs and 60 Co in soil were very small, indicating that HYDRUS 1D can be used to simulate the migration of radionuclides in farmland soil. Scenarios simulation results revealed that radionuclides were concentrated in the surface layer within 5 cm, but the migration depth has exceeded 10 cm soil depth, and even reaches up to 23.5 cm depth at high concentration level. The surface soil should be cleaned timely to protect groundwater with high level from radioactive contamination and further study should be done about horizontal transport and numerical simulation.

洪涝灾害是制约我国社会经济可持续发展的重要灾害.洪涝灾害评估研究是实现其有效防治的重要依据.本文根据《洪涝灾情评估标准》(SL 579—2012),选择死亡人口、受灾人口、农作物受灾面积、直接经济损失、水利设施经济损失、倒塌房屋、骨干交通中断历时、城市受淹历时、生命线工程中断历时等内容作为评估指标,以2017年度重庆市洪涝灾害作为研究对象,探讨境内暴雨洪灾分布规律.研究结果显示,2017年重庆市境内发生的13次区域性暴雨和1次局部暴雨,共计造成1.41×106人受灾,直接经济损失1.594×109元,其中,9月洪涝灾害损失最为严重.从受灾区域分布来看,渝东北开州、万州、巫溪等区(县)损失严重,渝西部地区灾害损失相对较轻.从场次洪涝灾害和年度洪涝评估结果来看,2017年属一般洪涝灾害年.本研究可为洪涝灾害评估提供方法借鉴,为暴雨洪灾防御工作提供数据与理论支撑.

生态护岸是土木工程与生态工程相结合的护岸形式,对保护岸坡稳定和河岸生态系统健康起着重要作用.从功能、技术、形式、评价四个方面对生态护岸的研究工作进行梳理,总结出生态护岸具有防洪护堤、净化、生态、景观四个方面的功能,论述了自然原型、半自然型、多自然型三种生态护岸类型的优缺点及适用范围.通过对不同的评价方法进行分析,并从安全性、生态性、景观性、社会经济性等方面建立河道生态护岸综合评价全指标体系,阐述目前生态护岸研究存在的问题,以期为生态护岸技术的发展提供理论基础并明晰研究方向.

干热河谷是我国西南地区一种特殊的自然景观,生态环境极端脆弱,加之消落带涉及面广,类型复杂,自我修复缓慢,增加了干热河谷生态治理的难度.为明确干热河谷生态治理的发展方向,介绍了干热河谷的基本情况,系统回顾了土壤类型、理化性质、水分分布和植被恢复技术、种类选择以及消落带治理方面的研究进展.目前干热河谷生态治理存在微观研究不够深入、缺乏长期动态监测、生态恢复效益评估指标单一化等不足,亟需应用先进技术手段,合理筛选优良的当地植物种类,建立生态环境长期动态监测与评估体系,加强生态系统自我修复功能,更科学有效地开展干热河谷生态治理.

金沙江干热河谷是我国重要的水利水电开发区.该区域水电站水库建成运行后将产生大面积库区消落带,严重威胁当地生态环境.本文从金沙江干热河谷水电站库区消落带植被现状、物种筛选、植物生理生态响应、植被恢复模式与技术、恢复生态效益评价等方面概括总结了该区域植被恢复研究进展与现状.针对金沙江干热河谷水电站库区消落带现有植被恢复研究实践不足的现状,提出该区域植被恢复宜根据地形地貌,结合生物技术和工程技术,综合利用多种生活型植物的植被恢复思路,指出金沙江干热河谷水电站库区消落带植被恢复未来研究重点,包括实践与示范、生态系统长期动态监测和管理政策研究等方向.

伴随着金沙江下游大型水电站的陆续建成,库区消落带将大规模形成并带来一系列生态环境问题.植被是消落带生态系统重要的组成部分,其演变对库岸稳定、水土保持、生物多样性和环境美化等方面具有深远的影响.通过系统回顾消落带植被恢复的研究进展,结合野外考察资料,从试验选址、适生物种选择、配置模式、种植与管护等方面总结消落带植被修复成果及经验,探讨了干热河谷消落带植被修复试验思路,明确了修复试验重点关注的方面,提出了抗旱耐淹物种选择的原则、条件和流程,并列出了适生植物物种推荐名录和植物梯级配置模式,以期为干热河谷消落带植被修复科研与实践提供参考.

在市级水土保持区划的基础上,根据江津区各镇街自然地理条件、土地利用现状等分析水土流失现状与分布特点,进一步对江津区进行五级分区划分.采用图层叠加分析法,将全区划分为北部城区人居环境维护区、中部浅丘土壤保持区、南部低山生态维护区等3个不同的水土保持分区,并根据各分区的特点因地制宜地提出相应的生产发展方向、水土流失治理要求或防治措施,以期指导各分区科学开展水土保持工作.

The risk of mountain flood disasters is the fundamental factor restricting the occurrence of disasters. The analysis and assessment of disaster risks is the basis for disaster risk management. Through the investigation of mountain flood disasters from 2013 to 2015, the basic information such as hydrometeorology, topography, socio-economic and mountain flood disaster prevention and control situation in mountain flood disaster prevention and control areas were found out. Taking the city of mountains-Chongqing as an ex-ample, this paper considered the results of mountain flood disaster investigation and evaluation in recent years, and divided the risk evaluation indicators into two types of first-level indicators: rainfall and under-lying surface, and the secondary indicators were subdivided into comprehensive rainstorm indicators, critical rainfall, topographic relief, land use convergence capacity, soil texture and river network density. Using AHP to set the weight coefficient of each level indicators, those showed that heavy rain conditions, critical rainfall and topographic relief were important factors impacting the mountain flood disasters, and the land use convergence capacity had the minimum weight coefficient. Through GIS superposition analysis, the risk index of mountain flood disasters in the region were obtained. The western, southeastern and northeastern Chongqing were high risk areas for mountain flood disasters, which provided decision-making basis for mountain flood disaster risk management.

通过现场调查,分析了重庆市重要水源地在污水、垃圾、沟渠、农业面源污染、水土流失、人居环境等方面存在的问题,探讨了重庆市生态清洁小流域(重要水源地)建设理念与思路.研究表明,根据地形地势及人类活动情况,因地制宜、因害设防从山顶到水源区周边依次建设“生态修复、生态治理、生态保护”水源保护三道防线进行清洁小流域(重要水源地)治理措施布设,可为重庆市后续生态清洁小流域(重要水源地)建设提供参考.

An in-depth analysis is carried out on comprehensive drought level, drought empirical frequency, precipitation and anomaly distribution and drought - resistant infrastructure construction in Chongqing based on the data of drought,meteoro-logical phenomena,water conservancy facilities from 1990 to 2016. The results showed that:①The drought occurred in different degrees every year from 1990-2016 in Chongqing. The agricultural drought level was medium with the annual average agricultur-al drought index of 0.54,and the level of drinking difficulty due to drought is also medium with annual 2.1373 million people suffering from drinking difficulty over the years. Meanwhile, the drought's level of drinking water difficulty and agriculture all show a weakening trend year by year. ② The frequency of different drought levels is different. The drought frequency of light, moderate,serious and extraordinary severe is 48.15%,44.45%,3.70%,3.70%,respectively. In general,the drought level was light in Chongqing. ③The causes of drought are meteorological,regional,man-made and other factors. The main counter-measures of drought disaster are speeding up the pace of water ecological civilization construction,increasing the quantity of water conservancy facilities and strengthening the construction of soil and water conservation projects and information technology pro-jects.

开展重要水源地生态清洁小流域建设,能够涵养水源,减少水土流失,控制面源污染.以重庆市生态清洁小流域建设实施方案为例,阐述了重庆市生态清洁小流域建设模式与管理情况,旨在为同类地区生态清洁小流域建设提供借鉴,并为今后水土保持工作的开展提供良好保障.

A case study was conducted in a small watershed of Sichuan hilly basin. In order to eva-luate the effect of land use type on soil characteristics, the soil physical and chemical properties of the 0-10 and 10-20 cm soil layers were analyzed through comparison between bare land and four land use types i.e., slope cropland, leveled cropland, orange forest and conservation forest. The results suggested that capillary porosity, non-capillary porosity, total porosity, and contents of soil organic matter, total nitrogen, total phosphorus, alkali-hydrolysis nitrogen, available phosphorus and available potassium under the same land use type in the 0-10 cm soil layer were more than those in the 10-20 cm soil layer, while the soil bulk density was the opposite. Moreover, there was no significant difference in total potassium between the two soil layers. The orange forest had the largest capillary porosity, non-capillary porosity, total porosity, the highest contents of total phosphorus, available phosphorus and the smallest soil bulk density under the same soil layer. The content of soil organic matter was highest under the conservation forest in the 0-10 cm soil layer and highest under the orange forest in the 10-20 cm soil layer. The order of grey correlation was conservation forest (0.9441)> orange forest (0.8858)> leveled cropland (0.6300)> bare land (0.5397)> slope cropland (0.4714) for the 0-10 cm soil layer, and conservation forest (0.8919) > orange forest (0.8401)> leveled cropland (0.5773)> bare land (0.5301)> slope cropland (0.5175) for the 10-20 cm soil layer. In conclusion, conservation forest was the best type to improve soil physical and chemical properties, and slope cropland was the worst type.

通过设置顺坡耕作对照(CK)、顺坡耕作农家肥和化肥配合施用(T1)、顺坡耕作单施化肥(T2)、顺坡耕作单施化肥增量(T3)与横坡垄作单施化肥(T4)处理,对不同施肥水平与耕作方式下坡面产流特征、磷素流失量以及作物生物量、氮磷吸收量进行了长期(2008-2012年)定位观测.结果表明:不同施肥、耕作处理间产流量、磷素流失量差异均达到显著性水平,不同施肥与耕作下产流量、TP、TDP流失量均以不施肥处理最大,不同施肥处理产流量依次为CK＞T3＞T2＞T1＞T4,T1、T2、T3比对照处理产流量分别减少35.69％,29.63％,16.82％,T4比T2处理减少25.94％;TP流失量依次为CK＞T3＞T2＞T1＞T4,与对照相比,T1、T2、T3处理分别较CK减少33.33％,31.25％,25％;TDP流失量依次为CK＞T3=T2＞T1＞T4,T1、T2、T3处理分别较对照减少30％,20％,20％,T4处理TP、TDP流失量比T2处理分别减少34.52％,24.72％.磷素流失以颗粒态为主,TDP/TP年均仅为26.41％.施肥与耕作对紫色土区作物生物量、氮磷吸收量均有显著性的影响,对照处理作物生物量、氮磷吸收量均低于其他施肥处理,施肥处理有助于增加作物生物量和氮磷的吸收量.相关分析表明:作物生物量、氮磷吸收量与径流量、TP、TDP均呈负相关关系,说明作物地上部分生物量越大,氮磷的利用率越高,坡面产流量和土壤养分的流失就越少.施肥能够很好地控制径流磷素的流失,以横坡垄作、农家肥和化肥配合施用最佳.

分析了川中丘陵区不同土地利用方式(坡耕地、梯平地、核桃林、甜橙林、水保林、裸地)下表层(0～20 cm)土壤理化性状,并运用主成分分析法计算土壤质量综合指数以评价土壤质量.结果表明,不同土地利用方式下土壤理化性状差异显著,核桃林、甜橙林、水保林土壤贮水量、土壤孔隙度、平均入渗率、前90 min渗透总量、全氮、碱解氮、有机质、全磷和有效磷等均优于其他土地利用方式;不同土地利用方式下土壤质量综合指数表现为核桃林(0.324)＞甜橙林(0.120)＞水保林(-0.010)＞梯平地(-0.021)＞坡耕地(-0.112)＞裸地(-0.288),核桃林对土壤质量的改善效果最明显,裸地最差.核桃林是川中丘陵区小流域治理的最佳选择模式.

The exploration of the fractal features of soil micro-aggregates under different governance patterns of small watershed can provide scientific basis for vegetation restoration and for soil and water loss control in the hilly areas of Sichuan Hilly Basin. Thus this paper analyzed the composition and fractal features of soil micro-aggregates and its relationship with soil physicochemical properties. The results showed that soil micro-aggregates of 0.01-0.05 mm size were dominant aggregates in 0-10 cm soil layer (28.63%) and 10-20 cm soil layer (28.04%). This was followed by soil micro-aggregates of 0.001-0.005 mm size for 0-10 cm soil layer (25.90%) and 10-20 cm soil layer (26.33%). Significant differences were observed among different patterns of governance. The range of fractal features of soil micro-aggregates was 2.643-2.717. The sequence of fractal features of soil micro-aggregates for dif-ferent governance patterns was conservation forest<orange forest<walnut forest<bare-land<slope-terrace<grading of slope land. Linear relation between fractal features and composition of soil micro-aggregates was observed. Fractal features of soil micro-aggre-gates showed significant positive correlations with available K and total K. However, negative correlations were noted between frac-tal features of soil micro-aggregates and total soil porosity, alkali-hydrolyzable N, total N and organic matter. The fractal features of soil micro-aggregates better reflected the physicochemical properties of soils in the hilly areas of central Sichuan Basin. Woodland was the best mode for vegetation restoration and controlling soil and water loss in the basin.